User Guide

QUICK GUIDE | OmniCTRL (Temperature)
15
11
LOLIGO
®
SYSTEMS1.0
CALIBRATION, CLEANING, AND MAINTENANCE
pH -> CO₂ conversion: Calibrate (13) the WTW SenTix HWD pH probe before conversion.
Prepare three water samples of the same quality (i.e. buer capacity) as the water used for
experiments, and keep water temperature constant and the same.
Use a gas mixing pump (Wösthof), mass ow cells, or ready-made gas mix to bubble the three
samples at three dierent pCO₂ levels within the range of your experiment min/max pCO₂ level.
Place the SenTix HWD pH probe in the first water sample, click the to measure pH, and
then type in the corresponding pCO₂ level. Click to add the next measurement point (11).
Perform three measurements per water sample to ensure stabilized readings. The conversion is
now done.
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100 % air sat. 0 % air sat.
O
2
N
2
14
14.1
Calibrate a Witrox oxygen sensor: In OmniCTRL > Main menu > Calibration > Choose Witrox
instrument. Click on the relevant channel ( CH1-CH4) to open the channel calibration menu
(14). Select the type of temperature input (Witrox controlled or User dened) and then perform
a Manual 2-point calibration (14 and 14.1):
a. Place the sensor tip in a mixed air-equilibrated water sample. This can be achieved
by purging atmospheric air into sample water, e.g. with an air pump.
b. Wait for the phase reading (sensor signal) to stabilize and then click
Read current values to save the current value as the HIGH calibration value
(100 % air saturation).
c. Transfer the sensor to an oxygen free water sample, e.g. by purging nitrogen gas
into sample water or by dissolving ~10 grams of Na
2
SO
3
in 500 ml of distilled
water.
d. Wait for the phase reading to stabilize and then click Read current values to save
the current sensor signals as the LOW calibration value (0 % air saturation).
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How to clean... In general, clean each instrument and sensor between uses.
• WTW probes: Please follow the cleaning instructions provided in the manual for the
CellOx 325, TetraCon 325, or SenTix HWD probe. Each manual can be found at:
loligosystems.com/manual
• Witrox oxygen sensor: Use a mild soap solution or bleach, and rinse with demi water.
Then dry (15).
• WTW and Witrox meters: Wipe the outside of the measuring instrument with a damp,
lint-free cloth. Disinfect the housing with isopropanol as required. Avoid contact with
acetone or similar detergents that contain solvents.
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Store all sensors in a dark, dry place between trials. Avoid exposing the uorescent dye on the
Witrox oxygen sensor to UV light. UV light will bleach the sensor dye and decrease the signal
strength (amplitude).
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b
b
d
d
When to calibrate... In general, you should perform a new sensor calibration if you experience
sensor performance issues (e.g. signal drift). Otherwise, a new calibraiton is recommended:
• WTW Oxi 3310 (CellOx 325): When the probe symbol ashes (after the set calibration
interval has expired (150 days as standard)) or when using a new probe.
• WTW Cond 3310 (TetraCon 325): Every 6 months or when using a new probe.
• WTW pH 3310 (SenTix HWD): When the probe symbol ashes (after the set calibration
interval has expired (7 days as standard)) or when using a new probe.
• Witrox: When the % air sat. level drifts with > +/-10 % or when using a new oxygen
sensor. The temp. probe is pre-calibrated and cannot be manually calibrated.
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Calibrate a WTW probe: Please see the respective WTW meter user manual for more
instructions. Each manual can be found at: loligosystems.com/manuals
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a c
MILD SOAP/
BLEACH
WATER
DRY